Dashpot



J. W. BROWN, JR.

DASHPOT.

APPLICATION FlL-ED JULY 19.1921.

1;,434319? Patented Oct. 311, 1922.

WITNESSES: INVENTOR.

fiwf mam @mw .ited 3i,

JOHN WILSON BROWN, JR., OF PHILADELPHIA, PENNSYLVANIA.

DASHPOT.

Application filed July 19, 1921.

T 0 a-ZZ whom it may concern:

Be it known that 1, JOHN lVILsoN BEO'W'N, Jr, a citizen or" the United States residing in hiladelphia, Pennsylvania, have invented a new and improved Dashpot, oi. which the following is a specification.

The object of my invention is to provide a dash-pot, for use with a rod capable oi? endwise motion, which shall retard the motion in either direction of such rod without in any degree affecting the final position which such rod may take due to the forces acting upon it. Further to provide a simple and economical construction oisuch dashpot.

In the accompanying drawings; Fig. l is a plan view of my improved dash-pot; Fig. 2 is a v .rtical sectional view of the same; Fig. 3 is a vertical sectional view of a part of the same showing a modification.

A. is a cylinder closed at its lower end and having a flange b at its upper end; C is a cylindrical casing having a flange (Z by which it is secured to A, a plate 6 and a cylindrical portion 7 connecting (Z and c. In 7 are one or more openings g. The plate 6 fits moderately closely in the bore of cylinder A and has a hole 72 through which passes the rod I which carries the piston J.

The rod 1 is the member whose motion produced by other mechanism is to be retarded. The outer diameter of the piston J is smaller than the bore cylinder A. so as to permit passage of fluid from one side of the piston to the other at a rate depending upon the pressure developed in the fluid. The amount by which the piston is smaller than the bore of the cylinder is determined. in any case by the exact amount of retardation desired to be applied to the movement of the rod 1. Instead of the piston J being smaller than the bore of A it may fit said bore and the necessary passage be provided by a hole through said piston as shown at 70 Fig. 3, or both methods may be employed. From a point in cylinder A. above the plate 6 a passage Z runs to a. point in the cylinder A below the lowest travel of the piston. This passage is not in all cases essential to my invention but I prefer to use it for reasons which will be stated later. The cylinder A is filled with liquid to a point above the top of plate 6. The volume of the cavities in the cylinder eel-m1 No. 486,002.

A above plate 6 and within cylindrical cas ing C is such that by no possibility can suflicient liquid work up from below plate 6 to fill said. cavities. It will be noted that at 1110 point in the apparatus is it necessary to provide a liquid-tight joint.

In operation it is evident that when motion is imparted to the red I said motion will be resisted by the liquid, the amount oi. such resistance being fixed by the speed oi? movement of the rod and by the space prodded for passage of liquid around the piston. lit the mot-ion is in a downward di.-- rection the liquid is restrained from bodily motion with the piston by the fact that any increment in volume above the piston must be supplied either by passage around the piston or by suction through such crevices as may exist at points m and ii. In like main ner in case of upward movement any decrease in the volume above the piston must be obtained by passage of liquid around the piston or by forcing liquid through the same crevices.

in order to provide tor a prompt return to the lo ver part of the cylinder of any fluid which may be forced up through the crevices at m and n the passage Z is provided. However, this passage can in many cases be dispensed with and such fluid allowed to be driven back through the crevices at m and a by atmospheric pressure.

Since there is no attempt made to pro duce a tight joint at the point an it is evident that there is no friction at this point and that the final position of the rod T is in no wise affected by the action of the dashpot.

l: claim 1. The combination oil a cylinder closed at the bottom, a plate located at a point below the upper end of said cylinder, a rod passing through said plate, a piston secured to said rod and a fluid filling said cylinder up to or above said plate.

2. The combination of a cylinder closed at the bottom, a plate located. at a uoint below the upper end of said cylinder, a rod passing through said plate, a piston secured to said rod, a passage connecting the bore of the cylinder at a point above said plate to the bore of the cylinder at a point below the lowest position oi said piston.

JOHN WILSON BROWN, JR. 

